Dumbbell



FIG. 1 is a perspective view showing one embodiment of the new design for a dumbbell;

FIG. 2 is a front view according to one embodiment of the new design;

FIG. 3 is a rear view according to one embodiment of the new design;

FIG. 4 is a right side view according to one embodiment of the new design;

FIG. 5 is a left side view according to one embodiment of the new design;

FIG. 6 is a top view according to one embodiment of the new design; and,

FIG. 7 is a bottom view according to one embodiment of the new design. 

CLAIM The ornamental design for a dumbbell, as shown and described. 